1. Field of the Invention
This invention relates to a mobile terminal communication system wherein radio communication is performed between a mobile terminal and another communication terminal through a radio base station apparatus.
2. Description of the Related Art
Since mobile terminal communication uses a radio circuit, communication interruption is much more likely to be caused by deterioration of a radio circuit condition or movement of the mobile terminal out of a radio service area than in communication in which a fixed terminal is used. Once communication interruption occurs, a call must be originated again from the origination side terminal or the termination side terminal to the other party terminal.
In this manner, the mobile terminal communication has a subject to be solved in that, once communication interruption occurs, a call must be originated again from the origination side or the termination side.
A similar scheme is disclosed, for example, in Japanese Patent Laid-Open No. 45990/1994. According to the scheme, a reception level value of a radio wave of a communication channel being received by a mobile terminal is detected. When the reception level value is lower than a prescribed value, one of level values of radio waves of communication channels of other radio base stations is selected. Then, the communication channel of the selected level value is used as one of dual communication circuits thereby to form communication channels with the two different radio base stations. However, the scheme does not successfully solve the subject described above as yet.
It is an object of the present invention to provide a mobile terminal communication system wherein, when communication interruption occurs, communication is re-started automatically without labor by a user to perform a call re-origination operation.
In order to attain the object described above, according to the present invention, if communication interruption occurs during communication between terminals, then a call is originated from a network side to the terminals and, only when a response is received from both of the terminals, communication is re-started automatically.
More particularly, according to the present invention, there is provided a mobile terminal communication system which allows radio communication between a mobile terminal and another communication terminal through a radio base station apparatus, comprising a subscriber number storage section provided in an exchange, which is a higher-rank apparatus than the radio base station apparatus, for temporarily storing subscriber numbers of origination and termination side terminals, a terminal type discrimination section provided in the exchange for discriminating from the subscriber numbers whether each of the communication terminals is a fixed terminal or a mobile terminal, a position information data base section provided in the exchange for storing, when a result of the discrimination by the terminal type discrimination section indicates that any of the communication terminals is a mobile terminal, current position information of the mobile terminal based on a position registration request signal from the mobile terminal, a communication end discrimination section provided in the exchange for discriminating whether or not the communication between the terminals has ended normally or abnormally, an automatic call origination control section provided in the exchange for automatically calling the terminals when a result of the discrimination by the communication end discrimination section indicates that the communication between the terminals has ended abnormally, and a timer section for causing the automatic call origination control section to operate for a fixed period of time.
In the mobile terminal communication system, subscriber numbers of origination and termination side terminals are temporarily stored into the subscriber number storage section of the exchange. Then, the terminal type discrimination section discriminates from the subscriber numbers whether each of the communication terminals is a fixed terminal or a mobile terminal. When the result of the discrimination indicates that any of the communication terminals is a mobile terminal, the position information database section stores current position information of the mobile terminal based on a position registration request signal from the mobile terminal.
If the communication between the terminals comes to an end in this state, then the communication end discrimination section discriminates whether or not the communication between the terminals has ended normally or abnormally. If the result of the discrimination by the communication end discrimination section indicates that the communication between the terminals has ended abnormally, then the automatic call origination control section operates for a fixed period of time under the control of the timer section. While the automatic call origination control section operates for the fixed period of time in this manner, it automatically calls the terminals. Then, only when a response is received from both of the terminals, re-starting of communication is enabled. Consequently, labor for performing a call re-origination operation can be eliminated.
Thus, even if interruption of communication occurs in mobile terminal communication, the two terminals are called automatically from the network side, and communication can be re-started when both terminals respond to the call. Consequently, the user of either terminal need not perform a call re-origination operation. Further, even if a mobile terminal moves into a different radio service area after occurrence of interruption of communication, the mobile terminal is called with the latest position information referred to. Consequently, there is an effect that the mobile terminal can be called without fail.
Preferably, when a radio circuit is disconnected by deterioration of a radio circuit condition or a like cause to interrupt the communication while the communication is proceeding between the origination side terminal and the termination side terminal, the automatic call origination control section automatically originates a call to the terminals based on the subscriber number information stored in the subscriber number storage section and radio service area information of an area or areas in which the mobile terminal or terminals are present stored in the position information database section, and re-starts communication if a response is received from both of the terminals.
Preferably, if any of the terminals moves into a different radio service area after it is discriminated that the communication between the terminals has ended abnormally, then the automatic call origination control section refers to new position information, which is stored into the position information database section when the terminal issues a position registration request in the radio service area after the movement, to call the mobile terminal having moved to the different radio service area.
Preferably, if any of the terminals does not respond within an automatic call origination time set in the timer section in advance, then the automatic call origination control section stops the terminal calling operation when the automatic call origination time elapses with the timer section.
The above and other objects, features and advantages of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings in which like parts or elements are denoted by like reference symbols.